[gmx-users] Slow Heating and Cooling
Martina Bertsch, PhD
mbe404 at lulu.it.northwestern.edu
Wed Jan 21 10:24:01 CET 2004
Greetings.
The simulated annealing algorithm implemented in Gromacs enables:
1) heating of structures from ref_t K to infinity, if the zero_temp_time
< 0 and
2) cooling from ref_t to 0 K, if the zero_temp_time > 0.
Other parameters are:
annealing = yes
tau_t, which if increased, allows for a slower heating.
Also, longer simulations imply slower cooling.
But, how exactly do I program a slow cooling from, say, 600 K to 500 K
(instead of 0 K)? Which mdp options do I use? If I say:
gen_vel = yes
gen_temp = 600
ref_t = 500
wouldn't temperature just quickly decrease to 500 K and remain at 500 K
for the rest of the simulation? Or could I force a slow temperature
decrease by increasing tau_t? What kind of value for tau_t would I need
so that the cooling from 600-500 K of a system of approx. 3000 atoms
takes 5 ps?
In the gmx archive, I found a discussion on the slow heating from 0
to100 K, in which Anton suggested setting init_t value to something
other than zero, but I did not quite understand what he meant. Would he,
please, elaborate? Is it at all possible to stop the heating at 100 K,
or to predict when the 0-to-infinity heating will reach 100 K?
I would appreciate your comments.
Martina
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